Vehicle fuel receptacle doors or caps, i.e., gasoline caps, and their associated fuel filler pipes are well known. Traditionally, a gas cap, or the door to access the gasoline receptacle, was located on the rear of vehicle along with a fuel filler pipe which connects the gas receptacle to the vehicle's fuel or gasoline tank. As an alternative to positioning the fuel receptacle at the rear of a vehicle, gas caps and receptacles have been positioned on a rear quarter panel or side of the vehicle. Gas caps and receptacles have also been located on the center of vehicle's hood. This placement is desirable for both functional and aesthetic reasons. Functionally, a center filled gas tank allows the vehicle to be refilled with equal convenience from either side of the vehicle. Additionally, if the driver is using a full service pump, he or she can easily monitor the entire refueling operation, thus reducing the chance that the wrong fuel will be transferred or that the wrong amount will be charged.
Moreover, in the racing environment, race cars may have the gasoline cap located on the center of the race car's hood. This also provides for expeditious refilling of the fuel tank from either side of the vehicle, and depending on the placement of the fuel pipe and fuel tank under the hood, can also allow for faster transfer of fuel, as the gas may not have to flow through a long fuel line from the fuel filler receptacle to the fuel tank. Additionally, the race car driver can easily monitor the refueling process, and know precisely when that process is completed, so no unnecessary time is wasted during a pit stop.
In addition, centering a gas cap on a hood at an approximately equal distance from either side of the vehicle contributes to the overall symmetry of the vehicle. For example, the side panels will now be identical as no fuel filler door, which breaks up the clean lines of vehicle, is needed. Finally, the location of the fuel filler receptacle cap on a vehicle's hood helps to create a more classic look to the vehicle, as certain historic or classic automobiles also placed the gasoline cap at a similar location.
Despite these advantages to a hood-centered fuel filler system, there are practical problems in creating such a system in a new vehicle, or modifying an existing vehicle. In either case, the rerouting of fuel lines can require expensive and time consuming modifications to a vehicle. For example, a hole may need to be cut in the luggage compartment wall to enable proper routing of the fuel filler pipe from the fuel receptacle to the fuel tank.
Also, the resulting vehicle is likely to have gasoline spilled on the hood. While such spills may not be a great concern in a racing environment, it is not acceptable for a non-racing vehicle.